The present invention relates to a tunnel construction and to tubbings used in such tunnel construction. Various types of tubbings are known in the art including steel reinforced concrete tubbings which are assembled into rings and the rings in turn are assembled to form the tunnel or rather the supporting tunnel tube.
The invention also relates to a tunnel construction using reinforced steel concrete tubbings wherein the individual tubbings in the rings are arranged in such a manner that the abutting joints of the tubbings of one ring are displaced relative to the abutting joints in the next adjacent ring. In other words, the ring built into the tunnel directly adjacent to the ring being built into the tunnel, has the joints between its tubbings angularly displaced relative to the respective joints of the adjacent ring whereby the angular displacement corresponds to a fixed distance. Normally, such a fixed distance will be equal to about one half the length of a tubbing.
In a so called shield tunneling machine, it is necessary to maintain the rings assembled from individual tubbings in position on the cylindrical tail end of the tunneling machine without the support provided by the surrounding earth or ground. This has resulted in difficulties because there is nothing holding the tubbings in place. In order to avoid such difficulties, it is known to secure the newly installed ring by means of screws to the ring already anchored in the ground. Such force transmitting screw connections require a precise fitting from ring to ring which in turn results in a rather substantial material and man hour expense.
It is also known to provide tongue and groove connections extending consecutively in the tubbings whereby adjacent rings mesh with each other. In this type of construction it is necessary to provide substantial play between the intermeshing parts in order to take into account practical construction considerations. Without such play it would not be possible to assemble the parts due to the unavoidable production tolerances. Such play between the tongue and groove in adjacent rings results in random contact points which in turn cause uncontrolled static conditions. Such uncontrolled static conditions are a substantial technical disadvantage, especially in tunnel tubes which must be constructed in a water tight manner. This is so because the uncontrolled static conditions may cause at certain points partial or localized overloads which in turn cause cracks.